Apparatus comprising expandable bistable tubulars and methods for their use in wellbores

ABSTRACT

A technique for connecting expandable tubulars. The technique comprises an expandable connector system that facilitates the connection of tubular components, such as tubulars used in wellbore environments.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This is a divisional of U.S. Ser. No. 10/035,994, filed Dec. 26,2001, which claims the benefit under 35 U.S.C. § 119(e) to U.S.Provisional Application Serial No. 60/263,934 filed Jan. 24, 2001.

FIELD OF THE INVENTION

[0002] This invention relates to equipment that can be used in thedrilling and completion of wellbores in an underground formation and inthe production of fluids from such wells; and is particularly toconnection systems for connecting a variety of tubulars used inwellbores.

BACKGROUND OF THE INVENTION

[0003] Fluids such as oil, natural gas and water are obtained from asubterranean geologic formation (a “reservoir”) by drilling a well thatpenetrates the fluid-bearing formation. Once the well has been drilledto a certain depth the borehole wall must be supported to preventcollapse. Conventional well drilling methods involve the installation ofa casing string and cementing between the casing and the borehole toprovide support for the borehole structure.

[0004] Within the casing or within the open wellbore, a variety oftubular components are utilized in, for example, preparation andservicing of the well and for the production of wellbore fluids. In someapplications, the use of expandable tubulars is becoming more desirable.In such applications, a tubular component is moved downhole and thenexpanded at a desired location within the wellbore. With these types oftubulars in particular, the connection of one tubular to another becomesdifficult. Connectors or connection systems designed for conventionaltubulars do not readily adapt to tubular members that are expanded.

[0005] The present invention is directed to overcoming, or at leastreducing the effects of one or more of the problems set forth above, andcan be useful in other applications as well.

SUMMARY OF THE INVENTION

[0006] According to one aspect of the present invention, a technique isprovided for connecting tubulars, such as those used within a wellbore.The technique is particularly amenable to use with expandable tubulars.The technique allows such expandable tubulars to be connected and yetexpanded as desired. Certain connectors utilized with this technique areparticularly helpful in connecting tubulars formed of bistable cellsthat facilitate expansion of the tubular from a contracted stable stateto an expanded stable state.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The invention will hereafter be described with reference to theaccompanying drawings, wherein like reference numerals denote likeelements, and:

[0008]FIGS. 1A and 1B are illustrations of the forces imposed to make abistable structure;

[0009]FIG. 2A and 2B show force-deflection curves of two bistablestructures;

[0010] FIGS. 3A-3F illustrate expanded and collapsed states of threebistable cells with various thickness ratios;

[0011]FIGS. 4A and 4B illustrate a bistable expandable tubular in itsexpanded and collapsed states;

[0012]FIGS. 4C and 4D illustrate a bistable expandable tubular incollapsed and expanded states within a wellbore;

[0013]FIGS. 5A and 5B illustrate an expandable packer type of deploymentdevice;

[0014]FIGS. 6A and 6B illustrate a mechanical packer type of deploymentdevice;

[0015] FIGS. 7A-7D illustrate an expandable swage type of deploymentdevice;

[0016] FIGS. 8A-8D illustrate a piston type of deployment device;

[0017]FIGS. 9A and 9B illustrate a plug type of deployment device;

[0018]FIGS. 10A and 10B illustrate a ball type of deployment device;

[0019]FIG. 11 is a schematic of a wellbore utilizing an expandablebistable tubular;

[0020]FIG. 12 illustrates a motor driven radial roller deploymentdevice;

[0021]FIG. 13 illustrates a hydraulically driven radial rollerdeployment device;

[0022]FIG. 14 is a partial side elevational view of an alternativeembodiment of the present invention;

[0023]FIG. 15 is a partial side elevational view of an alternativeembodiment of the present invention;

[0024] FIGS. 16A-E are partial elevational views of an alternativeembodiment of the present invention;

[0025] FIGS. 17A-D are partial perspective views of an alternativeembodiment of the present invention;

[0026]FIG. 18 is a side elevational view of an expandable slotted tubinghaving end extensions of the present invention;

[0027]FIG. 19 is a partial cross-sectional end view of an embodiment ofthe connector of the present invention;

[0028]FIG. 20 is a partial cross-sectional side view of an embodiment ofthe connector of the present invention;

[0029] FIGS. 21A-21E illustrate the sequential coupling of adjacenttubulars with a sand barrier;

[0030]FIG. 22 is a cross-sectional view taken generally along the axisof the connected tubulars illustrated in FIG. 21C;

[0031] FIGS. 23A-23C illustrate an alternate embodiment of theconnection system illustrated in FIGS. 21A-21C;

[0032] FIGS. 24A-24C illustrate another alternate embodiment of theconnection system illustrated in FIGS. 21A-21C;

[0033]FIG. 25 is a side view of a crossover device according to oneembodiment of the present invention;

[0034]FIG. 26 is a front view of an alternate embodiment of thecrossover device illustrated in FIG. 25; and

[0035] FIGS. 27A-27D illustrate another alternate embodiment of anexemplary connection system.

[0036] While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0037] Bistable devices used in the present invention can take advantageof a principle illustrated in FIGS. 1A and 1B. FIG. 1A shows a rod 10fixed at each end to rigid supports 12. If the rod 10 is subjected to anaxial force it begins to deform as shown in FIG. 1B. As the axial forceis increased rod 10 ultimately reaches its Euler buckling limit anddeflects to one of the two stable positions shown as 14 and 15. If thebuckled rod is now clamped in the buckled position, a force at rightangles to the long axis can cause the rod to move to either of thestable positions but to no other position. When the rod is subjected toa lateral force it must move through an angle β before deflecting to itsnew stable position.

[0038] Bistable systems are characterized by a force deflection curvesuch as those shown in FIGS. 2A and 2B. The externally applied force 16causes the rod 10 of FIG. 1B to move in the direction X and reaches amaximum 18 at the onset of shifting from one stable configuration to theother. Further deflection requires less force because the system now hasa negative spring rate and when the force becomes zero the deflection tothe second stable position is spontaneous.

[0039] The force deflection curve for this example is symmetrical and isillustrated in FIG. 2A. By introducing either a precurvature to the rodor an asymmetric cross section the force deflection curve can be madeasymmetric as shown in FIG. 2B. In this system the force 19 required tocause the rod to assume one stable position is greater than the force 20required to cause the reverse deflection. The force 20 must be greaterthan zero for the system to have bistable characteristics.

[0040] Bistable structures, sometimes referred to as toggle devices,have been used in industry for such devices as flexible discs, overcenter clamps, hold-down devices and quick release systems for tensioncables (such as in sailboat rigging backstays).

[0041] Instead of using the rigid supports as shown in FIGS. 1A and 1B,a cell can be constructed where the restraint is provided by curvedstruts connected at each end as shown in FIGS. 3A-3F. If both struts 21and 22 have the same thickness as shown in FIGS. 3A and 3B, the forcedeflection curve is linear and the cell lengthens when compressed fromits open position FIG. 3B to its closed position FIG. 3A. If the cellstruts have different thicknesses, as shown in FIGS. 3C-3F, the cell hasthe force deflection characteristics shown in FIG. 2B, and does notchange in length when it moves between its two stable positions. Anexpandable bistable tubular can thus be designed so that as the radialdimension expands, the axial length remains constant. Intone example, ifthe thickness ratio is over approximately 2:1, the heavier strut resistslongitudinal changes. By changing the ratio of thick-to-thin strutdimensions, the opening and closing forces can be changed. For example,FIGS. 3C and 3D illustrated a thickness ratio of approximately 3:1, andFIGS. 3E and 3F illustrate a thickness ratio of approximately 6:1.

[0042] An expandable bore bistable tubular, such as casing, a tube, apatch, or pipe, can be constructed with a series of circumferentialbistable connected cells 23 as shown in FIGS. 4A and 4B, where each thinstrut 21 is connected to a thick strut 22. The longitudinal flexibilityof such a tubular can be modified by changing the length of the cellsand by connecting each row of cells with a compliant link. Further, theforce deflection characteristics and the longitudinal flexibility canalso be altered by the design of the cell shape. FIG. 4A illustrates anexpandable bistable tubular 24 in its expanded configuration while FIG.4B illustrates the expandable bistable tubular 24 in its contracted orcollapsed configuration. Within this application the term “collapsed” isused to identify the configuration of the bistable element or device inthe stable state with the smallest diameter, it is not meant to implythat the element or device is damaged in any way. In the collapsedstate, bistable tubular 24 is readily introduced into a wellbore 29, asillustrated in FIG. 4C. Upon placement of the bistable tubular 24 at adesired wellbore location, it is expanded, as illustrated in FIG. 4D.

[0043] The geometry of the bistable cells is such that the tubularcross-section can be expanded in the radial direction to increase theoverall diameter of the tubular. As the tubular expands radially, thebistable cells deform elastically until a specific geometry is reached.At this point the bistable cells move, e.g. snap, to a final expandedgeometry. With some materials and/or bistable cell designs, enoughenergy can be released in the elastic deformation of the cell (as eachbistable cell snaps past the specific geometry) that the expanding cellsare able to initiate the expansion of adjoining bistable cells past thecritical bistable cell geometry. Depending on the deflection curves, aportion or even an entire length of bistable expandable tubular can beexpanded from a single point.

[0044] In like manner if radial compressive forces are exerted on anexpanded bistable tubular, it contracts radially and the bistable cellsdeform elastically until a critical geometry is reached. At this pointthe bistable cells snap to a final collapsed structure. In this way theexpansion of the bistable tubular is reversible and repeatable.Therefore the bistable tubular can be a reusable tool that isselectively changed between the expanded state as shown in FIG. 4A andthe collapsed state as shown in FIG. 4B.

[0045] In the collapsed state, as in FIG. 4B, the bistable expandabletubular is easily inserted into the wellbore and placed into position. Adeployment device is then used to change the configuration from thecollapsed state to the expanded state.

[0046] In the expanded state, as in FIG. 4A, design control of theelastic material properties of each bistable cell can be such that aconstant radial force can be applied by the tubular wall to theconstraining wellbore surface. The material properties and the geometricshape of the bistable cells can be designed to give certain desiredresults.

[0047] One example of designing for certain desired results is anexpandable bistable tubular string with more than one diameterthroughout the length of the string. This can be useful in boreholeswith varying diameters, whether designed that way or as a result ofunplanned occurrences such as formation washouts or keyseats within theborehole. This also can be beneficial when it is desired to have aportion of the bistable expandable device located inside a cased sectionof the well while another portion is located in an uncased section ofthe well. FIG. 11 illustrates one example of this condition. A wellbore40 is drilled from the surface 42 and comprises a cased section 44 andan openhole section 46. An expandable bistable device 48 having segments50, 52 with various diameters is placed in the well. The segment with alarger diameter 50 is used to stabilize the openhole section 46 of thewell, while the segment having a reduced diameter 52 is located insidethe cased section 44 of the well.

[0048] Bistable collars or connectors 24A (see FIG. 4C) can be designedto allow sections of the bistable expandable tubular to be joinedtogether into a string of useful lengths using the same principle asillustrated in FIG. 4A and 4B. This bistable connector 24A alsoincorporates a bistable cell design that allows it to expand radiallyusing the same mechanism as for the bistable expandable tubularcomponent. Exemplary bistable connectors have a diameter slightly largerthan the expandable tubular sections that are being joined. The bistableconnector is then placed over the ends of the two sections andmechanically attached to the expandable tubular sections. Mechanicalfasteners such as screws, rivets or bands can be used to connect theconnector to the tubular sections. The bistable connector typically isdesigned to have an expansion rate that is compatible with theexpandable tubular sections, so that it continues to connect the twosections after the expansion of the two segments and the connector.

[0049] Alternatively, the bistable connector can have a diameter smallerthan the two expandable tubular sections joined. Then, the connector isinserted inside of the ends of the tubulars and mechanically fastened asdiscussed above. Another embodiment would involve the machining of theends of the tubular sections on either their inner or outer surfaces toform an annular recess in which the connector is located. A connectordesigned to fit into the recess is placed in the recess. The connectorwould then be mechanically attached to the ends as described above. Inthis way the connector forms a relatively flush-type connection with thetubular sections.

[0050] A conveyance device 31 transports the bistable expandable tubularlengths and bistable connectors into the wellbore and to the correctposition. (See FIGS. 4C and 4D). The conveyance device may utilize oneor more mechanisms such as wireline cable, coiled tubing, coiled tubingwith wireline conductor, drill pipe, tubing or casing.

[0051] A deployment device 33 can be incorporated into the overallassembly to expand the bistable expandable tubular and connectors. (SeeFIGS. 4C and 4D). Deployment devices can be of numerous types such as aninflatable packer element, a mechanical packer element, an expandableswage, a piston apparatus, a mechanical actuator, an electricalsolenoid, a plug type apparatus, e.g. a conically shaped device pulledor pushed through the tubing, a ball type apparatus or a rotary typeexpander as further discussed below.

[0052] An inflatable packer element is shown in FIGS. 5A and 5B and is adevice with an inflatable bladder, element, or bellows incorporated intothe bistable expandable tubular system bottom hole assembly. In theillustration of FIG. 5A, the inflatable packer element 25 is locatedinside the entire length, or a portion, of the initial collapsed statebistable tubular 24 and any bistable expandable connectors (not shown).Once the bistable expandable tubular system is at the correct deploymentdepth, the inflatable packer element 25 is expanded radially by pumpingfluid into the device as shown in FIG. 5B. The inflation fluid can bepumped from the surface through tubing or drill pipe, a mechanical pump,or via a downhole electrical pump which is powered via wireline cable.As the inflatable packer element 25 expands, it forces the bistableexpandable tubular 24 to also expand radially. At a certain expansiondiameter, the inflatable packer element causes the bistable cells in thetubular to reach a critical geometry where the bistable “snap” effect isinitiated, and the bistable expandable tubular system expands to itsfinal diameter. Finally the inflatable packer element 25 is deflated andremoved from the deployed bistable expandable tubular 24.

[0053] A mechanical packer element is shown in FIGS. 6A and 6B and is adevice with a deformable plastic element 26 that expands radially whencompressed in the axial direction. The force to compress the element canbe provided through a compression mechanism 27, such as a screwmechanism, cam, or a hydraulic piston. The mechanical packer elementdeploys the bistable expandable tubulars and connectors in the same wayas the inflatable packer element. The deformable plastic element 26applies an outward radial force to the inner circumference of thebistable expandable tubulars and connectors, allowing them in turn toexpand from a contracted position (see FIG. 6A) to a final deploymentdiameter (see FIG. 6B).

[0054] An expandable swage is shown in FIGS. 7A-7D and comprises aseries of fingers 28 that are arranged radially around a conical mandrel30. FIGS. 7A and 7C show side and top views respectively. When themandrel 30 is pushed or pulled through the fingers 28 they expandradially outwards, as illustrated in FIGS. 7B and 7D. An expandableswage is used in the same manner as a mechanical packer element todeploy a bistable expandable tubular and connector.

[0055] A piston type apparatus is shown in FIGS. 8A-8D and comprises aseries of pistons 32 facing radially outwardly and used as a mechanismto expand the bistable expandable tubulars and connectors. Whenenergized, the pistons 32 apply a radially directed force to deploy thebis table expandable tubular assembly as per the inflatable packerelement. FIGS. 8A and 8C illustrate the pistons retracted while FIGS. 8Band 8D show the pistons extended. The piston type apparatus can beactuated hydraulically, mechanically or electrically.

[0056] A plug type actuator is illustrated in FIGS. 9A and 9B andcomprises a plug 34 that is pushed or pulled through the bistableexpandable tubulars 24 or connectors as shown in FIG. 9A. The plug issized to expand the bistable cells past their critical point where theywill snap to a final expanded diameter as shown in FIG. 9B.

[0057] A ball type actuator is shown in FIGS. 10A and 10B and operateswhen an oversized ball 36 is pumped through the middle of the bistableexpandable tubulars 24 and connectors. To prevent fluid losses throughthe cell slots, an expandable elastomer based liner 38 is run inside thebistable expandable tubular system. The liner 38 acts as a seal andallows the ball 36 to be hydraulically pumped through the bistabletubular 24 and connectors. The effect of pumping the ball 36 through thebistable expandable tubulars 24 and connectors is to expand the cellgeometry beyond the critical bistable point, allowing full expansion totake place as shown in FIG. 10B. Once the bistable expandable tubularsand connectors are expanded, the elastomer sleeve 38 and ball 36 arewithdrawn.

[0058] Radial roller type actuators also can be used to expand thebistable tubular sections. FIG. 12 illustrates a motor driven expandableradial roller tool. The tool comprises one or more sets of arms 58 thatare expanded to a set diameter by means of a mechanism and pivot. On theend of each set of arms is a roller 60. Centralizers 62 can be attachedto the tool to locate it correctly inside the wellbore and the bistabletubular 24. A motor 64 provides the force to rotate the whole assembly,thus turning the roller(s) circumferentially inside the wellbore. Theaxis of the roller(s) is such as to allow the roller(s) to rotate freelywhen brought into contact with the inner surface of the tubular. Eachroller can be conically-shaped in section to increase the contact areaof roller surface to the inner wall of the tubular. The rollers areinitially retracted and the tool is run inside the collapsed bistabletubular. The tool is then rotated by the motor 64, and rollers 60 aremoved outwardly to contact the inner surface of the bistable tubular.Once in contact with the tubular, the rollers are pivoted outwardly agreater distance to apply an outwardly radial force to the bistabletubular. The outward movement of the rollers can be accomplished viacentrifugal force or an appropriate actuator mechanism coupled betweenthe motor 64 and the rollers 60.

[0059] The final pivot position is adjusted to a point where thebistable tubular can be expanded to the final diameter. The tool is thenlongitudinally moved through the collapsed bistable tubular, while themotor continues to rotate the pivot arms and rollers. The rollers followa shallow helical path 66 inside the bistable tubular, expanding thebistable cells in their path. Once the bistable tubular is deployed, thetool rotation is stopped and the roller retracted. The tool is thenwithdrawn from the bistable tubular by a conveyance device 68 that alsocan be used to insert the tool.

[0060]FIG. 13 illustrates a hydraulically driven radial rollerdeployment device. The tool comprises one or more rollers 60 that arebrought into contact with the inner surface of the bistable tubular bymeans of a hydraulic piston 70. The outward radial force applied by therollers can be increased to a point where the bistable tubular expandsto its final diameter. Centralizers 62 can be attached to the tool tolocate it correctly inside the wellbore and bistable tubular 24. Therollers 60 are initially retracted and the tool is run into thecollapsed bistable tubular 24. The rollers 60 are then deployed and pushagainst the inside wall of the bistable tubular 24 to expand a portionof the tubular to its final diameter. The entire tool is then pushed orpulled longitudinally through the bistable tubular 24 expanding theentire length of bistable cells 23. Once the bistable tubular 24 isdeployed in its expanded state, the rollers 60 are retracted and thetool is withdrawn from the wellbore by the conveyance device 68 used toinsert it. By altering the axis of the rollers 60, the tool can berotated via a motor as it travels longitudinally through the bistabletubular 24.

[0061] Power to operate the deployment device can be drawn from one or acombination of sources such as: electrical power supplied either fromthe surface or stored in a battery arrangement along with the deploymentdevice, hydraulic power provided by surface or downhole pumps, turbinesor a fluid accumulator, and mechanical power supplied through anappropriate linkage actuated by movement applied at the surface orstored downhole such as in a spring mechanism.

[0062] The bistable expandable tubular system is designed so theinternal diameter of the deployed tubular is expanded to maintain amaximum cross-sectional area along the expandable tubular. This featureenables mono-bore wells to be constructed and facilitates elimination ofproblems associated with traditional wellbore casing systems where thecasing outside diameter must be stepped down many times, restrictingaccess, in long wellbores.

[0063] The bistable expandable tubular system can be applied in numerousapplications such as an expandable open hole liner where the bistableexpandable tubular 24 is used to support an open hole formation byexerting an external radial force on the wellbore surface. As bistabletubular 24 is radially expanded, the tubular moves into contact with thesurface forming wellbore 29. These radial forces help stabilize theformations and allow the drilling of wells with fewer conventionalcasing strings. The open hole liner also can comprise a material, e.g. awrapping, that reduces the rate of fluid loss from the wellbore into theformations. The wrapping can be made from a variety of materialsincluding expandable metallic and/or elastomeric materials. By reducingfluid loss into the formations, the expense of drilling fluids can bereduced and the risk of losing circulation and/or borehole collapse canbe minimized.

[0064] Liners also can be used within wellbore tubulars for purposessuch as corrosion protection. One example of a corrosive environment isthe environment that results when carbon dioxide is used to enhance oilrecovery from a producing formation. Carbon dioxide (CO₂) readily reactswith any water (H₂O) that is present to form carbonic acid (H₂CO₃).Other acids can also be generated, especially if sulfur compounds arepresent. Tubulars used to inject the carbon dioxide,as well as thoseused in producing wells are subject to greatly elevated corrosion rates.The present invention can be used to, place protective liners, e.g. abistable tubular 24, within an existing tubular to minimize thecorrosive effects and to extend the useful life of the wellboretubulars.

[0065] Another exemplary application involves use of the bistabletubular 24 as an expandable perforated liner. The open bistable cells inthe bistable expandable tubular allow unrestricted flow from theformation while providing a structure to stabilize the borehole.

[0066] Still another application of the bistable tubular 24 is as anexpandable sand screen where the bistable cells are sized to act as asand control screen. Also, a filter material can be combined with thebistable tubular as explained below. For example, an expandable screenelement can be affixed to the bistable expandable tubular. Theexpandable screen element can be formed as a wrapping around bistabletubular 24. It has been found that the imposition of hoop stress forcesonto the wall of a borehole will in itself help stabilize the formationand reduce or eliminate the influx of sand from the producing zones,even if no additional screen element is used.

[0067] The above described bistable expandable tubulars can be made in avariety of manners such as: cutting appropriately shaped paths throughthe wall of a tubular pipe thereby creating an expandable bistabledevice in its collapsed state; cutting patterns into a tubular pipethereby creating an expandable bistable device in its expanded state andthen compressing the device into its collapsed state; cuttingappropriate paths through a sheet of material, rolling the material intoa tubular shape and joining the ends to form an expandable bistabledevice in its collapsed state; or cutting patterns into a sheet ofmaterial, rolling the material into a tubular shape, joining theadjoining ends to form an expandable bistable device in its expandedstate and then compressing the device into its collapsed state.

[0068] The materials of construction for the bistable expandabletubulars can include those typically used within the oil and gasindustry such as carbon steel. They can also be made of specialty alloys(such as a monel, inconel, hastelloy or tungsten-based alloys) if theapplication requires.

[0069] The configurations shown for the bistable tubular 24 areillustrative of the operation of a basic bistable cell. Otherconfigurations may be suitable, but the concept presented is also validfor these other geometries.

[0070] Referring generally to FIGS. 14 and 15, a side elevational viewand a perspective view, respectively, are used to illustrated anexpandable tubing 80 made of bi-stable cells 81. As previouslydescribed, the bi-stable cells 81 are generally formed of a thin strut21 and a thick strut 22 which intersect at either end 84. In theexemplary embodiment shown in the figures, the end 82 of the tubing 80comprises a plurality of end extensions 86. The end extensions 86 areconnected to an end 84 of the cells 81 nearest the tubing end 82 so thatthe end extensions 86 extend beyond the cells 81 of the tubing. Thetubing may have end extensions on one or both ends thereof.

[0071] Further, although the figure illustrates an end extension on allof the endmost cells, alternative embodiments may have end extensions 86on some portion of such cells only. The end extensions 86 are useful forconnecting adjacent expandable tubings as further discussed below aswell as for other uses. Note that the end extensions do not undergodeformation as the tubing is expanded. The end extensions may beintegrally formed or otherwise attached such as by welding or otherattachment methods.

[0072] Referring generally to FIGS. 16A-E, a detailed sequence isillustrated of one embodiment of end extensions 86 being connected toadjacent tubings having an associated connector 90. As shown in thefigures, one of the end extensions 86 includes an opening 92 formedtherein. Although shown as a slot in the FIGS. 16A-E, the opening 92 maytake other forms such as a hole drilled in the end, collets, or othertypes of openings 92. The opening 92 of the disclosed embodiment forms anarrow outer portion 94 and a wide inner portion 96. The opening 92 alsomay have a slot 98 at the back of the opening 92. The end 100 of the endextension 86 has a slanted, or tapered, interior 102 and a slanted, ortapered, exterior 104. Although shown as slanted, the end 100 may beblunt, rounded or some other shape.

[0073] A pin 110 mounted to the end of a corresponding extension 86 hasa broad head 112 with a slanted forward face 114. The pin 110 is shapedand sized to mate with the opening 92. The figures show how the pin 110passes through the outer portion 94 of the opening 92. As the pin 110passes through the outer portion 94, the opposing sides flex outwardly(FIG. 16B) to accommodate the relatively larger head 112. Once the headis positioned in the inner portion 96 (FIG. 16C), the sides may flexback to their original position or near their original position. Theslot 98 may provide added resiliency to facilitate placement of the pin110 in the opening 92.

[0074] Once the head 112 is positioned inside the opening 92, sleeve 120slides over the mating pin 110 and opening 92 to maintain them in matingconnection (see FIGS. 16D and 16E). The slanted exterior 104 of the endextension 86 facilitates movement of the sleeve 120 thereon. Note thatthe sleeve may be replaced by a clip surrounding the mating pin 110 andopening 92 or other device that can maintain the relative position ofthe mating pieces.

[0075] It should also be noted that in one embodiment, the head 112provides for some plastic deformation of the sides of the end extension86 so that the sides remain slightly flared. The flared sides providefor increased friction useful in holding the sleeve in place.Alternatively the end extensions 86 may provide detents or othermechanisms to prevent the sleeve from slipping out of position.

[0076] Referring to FIGS. 17A-D, an alternative embodiment forconnecting the end extensions 86 of adjacent tubings is illustrated. Inthis embodiment, both end extensions 86 have openings 92 formed therein.Once the end extensions 86 are positioned adjacent one another, matingconnectors 122 are moved into the openings 92 to maintain the relativeposition of the end extensions 86. As with the prior embodiment, theconnector 122 has widened head portions 112 that fit within wide innerportions 96 of the openings 92. A sleeve 120 slides over the matingconnector 122 and openings 92 to help maintain their relative positions.Note that the connectors 122 may have detents or other features thateliminate the need for the sleeve 120. Alternatively, the sleeve 120 maybe replaced with a clip, adhesive, resin, tape, or other manner ofholding the connector 122 in the openings 92. Although the abovedescription relies on the use of end extensions 86 they may be omittedin certain alternative embodiments with the openings formed at the endof the endmost cells.

[0077] Also, note that other types of expandable tubings may benefitfrom the connection type taught herein. For example, as illustrated inFIG. 18, an expandable slotted tube 130 of the type disclosed in U.S.Pat. No. 5,366,012, issued Nov. 22, 1994 to Lohbeck has overlappinglongitudinal slots. As can be viewed in FIG. 18, tubing 130 has endextensions 86 with openings 92 formed therein. The end extensions andopenings may be used to connect the tubing 130 to an adjacent tubing ina manner similar to that previously described. As with the otherembodiments, these types of connectors readily allow expansion of theconnected ends of the tubulars along with the rest of the tubular asopposed to the traditional connection systems that are not as amenableto expansion.

[0078] In FIG. 19, another alternative embodiment is illustrated inwhich the connector 122 has sides 142 that slant inwardly approachingone end. The sides 140 of the mating opening 92 also slant inwardly suchthat the connector 122 may be placed in the opening in one directiononly. The tolerance between the opening 92 and the connector 122 holdsthe connector in place in one direction. The slanted surfaces 140, 142may be replaced with equivalents such as shoulders and the like. Theembodiment shown also has a clip 144 with resilient side arms anddetents 146 that mate with indentations 148 formed in the end extensions86. The detents 146 and indentations 148 mate to hold the clip 144 onthe end extension 86. The clip 144 is placed on the side through whichthe connector 122 is placed.

[0079] Illustrated in FIG. 20 is another alternative embodiment in whichthe openings 92 do not open to the ends of the end extensions 86. Aconnector 150 has side members 152 that are coupled to retention members154. Retention members 154 are sized to extend through the openings 92into engagement with side members 152. Side members 152 may be coupledto retention members by a variety of mechanisms including snap fits,permanent fixation or fasteners. The tensile strength of the combinedconnections should be sufficient to prevent separation of the connectedtubings. Accordingly, the connector may be formed of a material that isdifferent from the material of the tubing.

[0080] Referring generally to FIGS. 21A-21C, another embodiment of anexpandable connection system is illustrated. In this embodiment, a firsttubular 160 is coupled to a second tubular 162 by a connection system164. First tubular 160 and second tubular 162 may be comprised of aplurality of bistable cells, as described above. Additionally,connection system 164 may be designed to function similarly to theembodiments described above.

[0081] As illustrated, connection system 164 comprises a receiving end166 extending from first tubular 160 and an insertion end 168 extendingfrom second tubular 162. The exemplary receiving end 166 comprises aplurality of extensions 170 that define a plurality of openings 172 eachhaving a narrow outer portion 174 and a wider inner portion 176 similarto openings described above. Insertion end 168 comprises a plurality ofpins or broad heads 178 that may be tapered towards a leading edge forinsertion into openings 172 through the narrow outer portions 174. Eachof the pins 178 includes a recessed retention feature 179 designed toengage a corresponding retention feature 180 of each extension 170.Retention features 179 and 180 are designed to prevent inadvertentseparation of first tubular 160 and second tubular 162. Additionally, aretention member 181, e.g. an expandable slide cover, is mounted to atleast one of first tubular 160 and second tubular 162. In the embodimentillustrated, retention member 181 is slidably mounted to first tubular160 such that it may be moved over extensions 170 and pins 178 aftercoupling of first tubular 160 to second tubular 162 to secure theconnection. In the example illustrated, retention features 179 and 180do not extend radially outward beyond the outside diameter of firsttubular 160 and second tubular 162. Thus, the outside diameter of thecollective extensions of connector system 164 does not exceed theoutside diameters of first and second tubulars 160 and 162.

[0082] An exemplary retention member 181 is a slide cover comprising aplurality of separable sections 182 that each have a pair oflongitudinal openings 183 through which a pair of cooperating extensions170 are received (see FIGS. 21D and 21E). When the slide cover is in adisengaged position as illustrated in FIG. 21A, cooperating extensions170 may be sufficiently spread to receive a pin 178 as illustrated inFIG. 21B. Once extensions 170 and pins 178 are interlocked, 5 the slidecover is moved to an engaged position, as illustrated in FIG. 21C. Inthis engaged position, extensions 170 are prevented from spreading byvirtue of their capture within openings 183. Separable sections 182 maybe independent of each other or connected by an expandable material orflexible connection that permits radial expansion of retention member181.

[0083] Additionally, the slide cover may comprise one or more integratedlocking devices 184 used to hold the slide cover in its-engagedposition, although the locking devices also can be used to hold theslide cover in the disengaged position. An exemplary locking device 184comprises a plurality of threaded studs 185 threadably received throughcorresponding sections 182. One or more of the threaded studs 185 may berotated and moved radially inwardly to hold the slide cover or at leastthe corresponding section 182 at a desired location. For example, whenthe slide cover is moved to the engaged position, threaded studs 185 arerotated inwardly, as illustrated in FIGS. 21E and 22, to prevent theslide cover from being inadvertently moved to the disengaged position.Specifically, extensions 170 are designed to block movement of the studs185 towards a disengaged position once threaded radially inwardly asufficient amount.

[0084] Additionally, connection system 164 may comprise a sand barrier186 designed to limit the influx of sand through connection system 164.In this embodiment, sand barrier 186 is disposed along the interior ofconnection system 164. For example, at least a portion of sand barrier186 may be coupled to the interior of first tubular 160 such that itextends beyond extensions 170. (See FIG. 21A). When first tubular 160and second tubular 162 are moved together, sand barrier 186 moves intothe interior of second tubular 162 as pins 178 are inserted intoopenings 172, as illustrated best in FIG. 21B. Following insertion,slide cover 181 is moved towards second tubular 162 and over theinterlocked extensions 170 and 178 to further assist in preventingunwanted separation of the tubular components.

[0085] Referring generally to FIG. 22, one exemplary embodiment of thisinternal type of sand barrier is illustrated. In this embodiment, a sandbarrier sand sleeve 188 is connected to the interior of first tubular160 by, for example, a plurality of pins 190 received in correspondingslots 192 formed in tubular 160. Another exemplary mechanism forfastening sand barrier sleeve 188 to tubular 160 is a plurality ofweldments placed on selected portions of the tubular so as to notinterfere with expansion. Weldments can be used alone or in addition toother retention features, such as pins 190. A barrier cap 194 is affixedto second tubular 162 by, for example, pins 196 and/or appropriateweldments. Barrier cap 194 comprises a recessed region 198 for receivingand holding sand barrier sleeve 188 when first tubular 160 and secondtubular 162 are coupled together. A plurality of barrier sheets 199 maybe combined with or incorporated into sand sleeve 188. Exemplary barriersheets 199 comprise overlapping, metallic sheets that permit expansionof the sand barrier 186 without effecting blockage of sand influx. Otherexemplary barriers comprise woven filtration materials, slotted metallicsheets with slots sized according to desired filtration parameters, orelastomeric materials.

[0086] An alternate embodiment of the sand barrier is illustrated inFIGS. 23A-23C and labeled as sand barrier 200. In this embodiment, theillustrated connection system 164 is similar to that shown and describedin FIGS. 21A-21C. Sand barrier 200, however, is an external sand barriersimilar in design to the interior sand barrier 186, except disposed toslide over the exterior of connection system 164.

[0087] For example, sand barrier 200 may be attached along the exteriorof first tubular 160 by appropriate fasteners, weldments, etc., asillustrated best in FIGS. 23A and 23C. As insertion end 168 of secondtubular 162 is moved into engagement with receiving end 166 of firsttubular 160, sand barrier 200 moves over second tubular 162 and coversconnection system 164, as best illustrated in FIG. 23B. One exemplarysand barrier 200 comprises an outer shroud 202 covering one or morebarrier sheets 204 (see FIG. 23C), however a variety of layers andmaterials can be combined to create the sand barrier. An exemplary sandbarrier is made from a material that is hyperelastic, capable of shapememory, or made from other expandable materials, such as titaniumalloys, to achieve the desired expansion effect.

[0088] Another exemplary embodiment of a sand barrier is illustrated inFIGS. 24A-24C. In this embodiment, a sand barrier 210 comprises anexpandable shroud and filter layer 212 that is pulled over a firstrun-in guide 214, as illustrated in FIG. 24A. The shroud and filterlayer 212 is moved over run-in guide 214 (see FIG. 24B) until it ispositioned generally between run-in guide 214 and a secondary run-inguide 216, as illustrated best in FIG. 24C.

[0089] Referring generally to FIGS. 25 and 26, additional embodiments ofthe present invention are illustrated in the form of crossover devices.For example, in FIG. 25, an expandable crossover 220 is illustrated.Expandable crossover 220 comprises an expandable section 222 and a solidsection 224. Crossover 220 typically comprises a connector end 226having, for example, internal threads for threaded engagement with anadjacent component. Also, the expandable section may be formed with oneor more bistable cells.

[0090] Additionally, expandable crossover 220 comprises a connector 228generally opposite connector end 226. Connector 228 may be any of avariety of the connectors described above including, for example, aplurality of extension pins designed for receipt in correspondingextensions. Furthermore, any of the variety of sand barriers discussedabove can be combined with expandable crossover 220 proximate connector228.

[0091] Expandable section 222 also may comprise or be combined with avariety of other components. For example, sand filtration materials andouter shrouds may be incorporated into the design of expandable section222. Furthermore, expandable section 222 may be surrounded with anelastomeric material, e.g. rubber jacket, for a variety of applications.These are just a few examples illustrating the adaptability of thecrossover device.

[0092] In another embodiment illustrated in FIG. 26, the crossover is arigid crossover 230. Though the rigid crossover 230 is not expanded, itcan be combined with an expandable-style connector 232. With connector232, expandable sand barriers, such as those discussed above, can beincorporated into the design to limit the influx of sand throughconnector 232. Opposite connector 232, rigid crossover 230 comprises aconnector end 234 that may be tapered and comprise a threaded region236.

[0093] Referring generally to FIGS. 27A-27D, another technique isillustrated for coupling the first tubular 160 with the second tubular162. The technique may be utilized with expandable and non-expandabletubulars.

[0094] In this embodiment, a connector system 240 is used to couplefirst tubular 160 with second tubular 162. Connector system 240comprises a first connector portion 242 coupled to first tubular 160 anda second connector portion 244 coupled to second tubular 162. First andsecond connector portions 242, 244 may be separate components attachedto the corresponding tubulars, or they may be integrally formed with thetubulars.

[0095] First connector portion 242 comprises a plurality of extensions246 separated by gaps 248, as illustrated best in FIG. 27A. Similarly,second connector portion 244 comprises a plurality of axial extensions250 separated by axial gaps 252. Axial gaps 252 are sized to receiveextensions 246, and gaps 248 are sized to receive axial extensions 250,as illustrated in FIG.27B.

[0096] Furthermore, extensions 246 comprise a first interlock mechanism254, and axial extensions 250 comprise a second interlock mechanism 256designed to engage first interlock mechanism 254. Connector system 240becomes interlocked when extensions 246, 250 are moved axially intotheir cooperating gaps 252, 248, respectively, and tubulars 160 and 162are rotated with respect to each other, as illustrated best in FIG. 27C.In the specific embodiment illustrated, first interlock mechanism 254comprises a plurality of circumferentially oriented ridges 258 separatedby spaces 260. The circumferentially oriented ridges 258 extend radiallyinwardly.

[0097] Similarly, an exemplary second interlock mechanism 256 comprisesa plurality of outwardly extending ridges 262 separated by spaces 264.Outwardly extending ridges 262 are circumferentially oriented forreceipt in spaces 260 when first tubular 160 and second tubular 162 arerotated to interlock connector system 240. Similarly, ridges 258 aresized and oriented for receipt in spaces 264 when connector system 240is interlocked.

[0098] To secure the interlocking of extensions 246 with axialextensions 250, one or more sleeves, such as sliding covers 266, may bemounted over selected extensions, as illustrated in FIGS. 27C and 27D.For example, sliding cover or covers 266 may be slidably disposed on oneof the axial extensions 250. The sliding cover is positioned at alocation that does not interfere with the insertion of extensions 246into axial gaps 252 or the rotation of first interlock mechanism 254into engagement with second interlock mechanism 256, as illustrated bestin FIG. 27C.

[0099] Once interlocked, each of the one or more sliding covers 266 isslid over the mating first interlock mechanism 254 and second interlockmechanism 256, as illustrated best in FIG. 27D. The sliding cover 266 issized to prevent the interlocked ridges 258 and 262 from separatingand/or rotating with respect to each other. If desired, each slidingcover 266 may be held at a desired location over first interlockmechanism 254 and second interlock mechanism 256 by, for example, afriction fit, detents, set screws, a weldment or other fasteningmechanisms.

[0100] In some applications, first tubular 160 and/or second tubular 162are expanded within the wellbore. The unique design of interlockedextensions with gaps therebetween allows connector system 240 to beexpanded along with tubulars 160 and 162.

[0101] The particular embodiments disclosed herein are illustrativeonly, as the invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is therefore evident that theparticular embodiments disclosed above may be altered or modified andall such variations are considered within the scope and spirit of theinvention. Accordingly, the protection sought herein is as set forth inthe claims below.

What is claimed is:
 1. A system of expandable tubulars, comprising: afirst expandable tubular; a second expandable tubular; and a connectorsystem coupling the first expandable tubular to the second expandabletubular, the connector system having a plurality of interlockingextensions comprising receiving extensions and insertion extensions,each receiving extension having a connector opening with a narrow outerportion and a wider inner portion to interlockingly receive acorresponding insertion extension.
 2. The system as recited in claim 1,further comprising a slide cover positioned to secure the plurality ofinterlocking extensions.
 3. The system as recited in claim 1, whereineach insertion extension comprises a broad head for receipt in the widerinner portion.
 4. The system as recited in claim 3, wherein thereceiving extensions extend from an end of the first expandable tubularand the insertion extensions extend from an adjacent end of the secondexpandable tubular.
 5. The system as recited in claim 4, wherein thefirst expandable tubular comprises a plurality of bistable cells.
 6. Thesystem as recited in claim 5, wherein the second expandable tubularcomprises a plurality of bistable cells.
 7. The system as recited inclaim 6, wherein the connector system comprises a sand barrier.
 8. Thesystem as recited in claim 7, wherein the sand barrier is positionedalong the interior of the first expandable tubular and the secondexpandable tubular.
 9. The system as recited in claim 7, wherein thesand barrier is positioned along the exterior of the first expandabletubular and the second expandable tubular.
 10. A device that may be usedin a wellbore, comprising: an expandable tubular having a plurality ofbistable cells and an expandable connector end formed with a pluralityof extensions.
 11. The device as recited in claim 10, wherein eachextension of the plurality of extensions comprises an opening shaped forinsertion of an extension from an adjacent expandable tubular.
 12. Thedevice as recited in claim 10, wherein each extension of the pluralityof extensions comprises an insertion head for insertion into anextension from an adjacent expandable tubular.
 13. The device as recitedin claim 10, wherein the expandable tubular is expandable along aportion, the portion being less than its entire length.
 14. The deviceas recited in claim 10, wherein the expandable tubular comprises athreaded connector end generally opposite the expandable connector end.15. The device as recited in claim 10, wherein the expandable tubularcomprises a second expandable connector end generally opposite theexpandable connector end.
 16. A connector system for connecting a pairof adjacent tubulars, comprising: a plurality of connector portionsextending from a first tubular; and a plurality of correspondingconnector portions disposed at an end of a second tubular, the pluralityof connector portions being configured to interlockingly receive thecorresponding connector portions when the first tubular and the secondtubular are rotated with respect to each other.
 17. The connector systemas recited in claim 16, wherein each connector portion comprises aplurality of spaced circumferentially oriented ridges extending radiallyinward, and each corresponding connector portion comprises a pluralityof corresponding ridges extending radially outward for receipt betweenthe spaced circumferentially oriented ridges upon relative rotation ofthe first tubular and the second tubular.
 18. The connector system asrecited in claim 17, further comprising a sleeve disposed around atleast one of the connector portions.
 19. The connector system as recitedin claim 14, further comprising a sand barrier positioned along theplurality of connector portions and the plurality of correspondingconnector portions when engaged.
 20. The connector system as recited inclaim 18, wherein the sleeve comprises a slide cover sized to slide overan interlocked connector portion and corresponding connector portion.21. The connector system as recited in claim 16, wherein the firsttubular and the second tubular are expandable.
 22. A method of expandingtubulars, comprising: forming a first tubular and a second tubular froma plurality of bistable cells; coupling the first tubular to the secondtubular by a plurality of interlocking extensions; and radiallyexpanding the plurality of interlocking extensions during expansion ofthe first tubular and the second tubular.
 23. The method as recited inclaim 22, wherein coupling comprises axially moving the plurality ofinterlocking extensions into engagement and rotating the second tubularwith respect to the first tubular.
 24. The method as recited in claim22, further comprising forming the interlocking extensions with spaced,circumferentially oriented ridges.
 25. The method as recited in claim22, further comprising forming the plurality of interlocking extensionsfrom extensions having receiving openings and extensions having headssized for receipt in the receiving openings.
 26. The method as recitedin claim 22, further comprising securing the first tubular to the secondtubular with a retention sleeve.
 27. The method as recited in claim 22,further comprising placing an internal sand barrier along the pluralityof interlocking extensions.
 28. The method as recited in claim 22,further comprising placing an external sand barrier along the pluralityof interlocking extensions.
 29. A system for expanding tubulars,comprising: means for coupling a first bistable tubular to a secondbistable tubular; and means for radially expanding the plurality ofinterlocking extensions during expansion of the first bistable tubularand the second bistable tubular.
 30. The system as recited in claim 29,wherein the means for coupling comprises a plurality of interlockingfeatures.
 31. The system as recited in claim 29, wherein the means forradially expanding comprises an expansion device moved through alongitudinal opening of the first tubular and the second tubular.
 32. Asystem of expandable tubulars, comprising: a first expandable tubular; asecond expandable tubular coupled to the first expandable tubular via aconnector system; and a sand barrier disposed along the connectorsystem.
 33. The system as recited in claim 32, wherein the sand barrieris external to the connector system.
 34. The system as recited in claim32, wherein the sand barrier is internal to the connector system. 35.The system as recited in claim 32, wherein the first expandable tubularcomprises one or more bistable cells.
 36. The system as recited in claim32, wherein the second expandable tubular comprises one or more bistablecells.
 37. A device for use in a wellbore, comprising: a crossoverhaving an end formed as an expandable connector.
 38. The device asrecited in claim 37, further comprising a non-expandable end oppositethe end.
 39. The device as recited in claim 37, further comprising anexpandable tubular section.
 40. The device as recited in claim 39,wherein the expandable tubular section comprises a plurality of bistablecells.
 41. A system of expandable tubulars, comprising: a firstexpandable tubular; a second expandable tubular; and a slide covermounted on the first expandable tubular, wherein the slide cover may beslid into engagement with the second expandable tubular to secure thesecond expandable tubular to the first expandable tubular.
 42. Thesystem as recited in claim 41, further comprising a plurality ofinterloking extensions disposed at adjacent ends of the first and secondexpandable tubulars.
 43. The system as recited in claim 42, wherein theslide cover is disposed around the plurality of interlocking extensionsto secure them in interlocked engagement.
 44. The system as recited inclaim 41, wherein the first expandable tubular comprises a plurality ofbistable cells.
 45. The system as recited in claim 44, wherein thesecond expandable tubular comprises a plurality of bistable cells.
 46. Asystem for connecting tubulars, comprising: a first tubular; a secondtubular; and a connector system coupling the first tubular to the secondtubular, the first tubular having a plurality of receiving extensionsand the second tubular having a plurality of insertion extensions, eachreceiving extension being configured to interlockingly receive acorresponding insertion extension, wherein the outside diameter of theconnector system does not exceed the outside diameter of either thefirst tubular or the second tubular.
 47. The system as recited in claim46, further comprising a slide cover positioned to secure the pluralityof interlocked insertion extensions and receiving extensions.
 48. Thesystem as recited in claim 46, further comprising a sleeve disposedabout at least one interlocked receiving extension and insertionextension.
 49. The system as recited in claim 46, wherein the firstexpandable tubular comprises a plurality of bistable cells.
 50. Thesystem as recited in claim 49, wherein the second expandable tubularcomprises a plurality of bistable cells.
 51. The system as recited inclaim 46, wherein the connector system comprises a sand barrier.
 52. Thesystem as recited in claim 46, wherein the first tubular, the secondtubular and the connector system are radially expandable.
 53. The systemas recited in claim 46, wherein each receiving extension of theplurality of receiving extensions comprises an opening shaped tointerlockingly receive one of the insertion extensions.
 54. The systemas recited in claim 53, wherein each insertion extension of theplurality of insertion extensions comprises an insertion head forinsertion into the opening of an adjacent receiving extension.